I don't know about AWS Solutions Architecture specifically, but I've found that advanced learning typically doesn't come from "courses" in the traditional sense. More typically blogs, research papers, self-contained lectures, and textbooks. One unfortunate aspect of these is that they often tend to be filled with extreme levels of technical language and so there's often a difficulty finding that middle area, especially when you know enough to skim or skip intro works to a subject.

These seem particularly difficult to find though. Maybe someone knows of a listing that these can be found in aggregate and built by the communities? If not, might be worth building.